http://ur5fcm.h1.ru/schemes/gu74.html
PA with GK-71 for FT-840. PEP 500W. All HF bands, grounded grid. GK-71 is a ("good, old")
tube somewaht similar to GU-13 (813). It has however rather poor performance above, say
20MHz (my personal experience). The author (UA1FA) addresses that and uses this to his
advantage (no chance of parasitic oscillations!). This may be just another site with already
known design.